Fluid operated gear shifting mechanism



Patented Mar. *9, 1943 OFFICE FLUID OPERATED GEAR ',SHIFTIN G MECHANISM William G.-Hoelscher, Cincinnati, Ohio, assignor to The American Tool Works Company, Cincinnati, Ohio, a corporation of Ohio Application July .'18, 1940, Serial N0'. 346,185

3 Claims. (Cl. 277-424) This invention relates to fluid operated gear shifting or speed changing mechanisms. It is particularly directed to an improved apparatus and valve arrangement wherein the operations of selecting and shifting may be performed independently but through a common lever.

It has been the object of the present inventor to provide a control lever and valve arrangement constituting a gear selecting and sluiting l means which is compactly arranged and easily operated from a single lever; this lever in one direction of movement selecting the speed and in another directionA of movement effecting the gear change.

This object may be a'chievel in a structure including a valve shifting plunger movable axially for admitting the fluid under pressure from, the point of Asupply to the selector valve and a rotfta'nle element associated with said plunger valve, the rotation of which will operate the selector valve. These movements, that is, lthe axial plunger valve movement and the rotatable movement, are brought about through a single lever which has a compound movement, the respec-y tive movements being independently performed.

The subject matter of this application pertaining to the iluid gear shifting apparatus apart from the valve organization above set forth, is described and claimed in a copending application filed as a division of this application on August 22, 1942, and bearing Serial No. 455,761.

Other' objects and certain advantages will be more fully apparent from a description of the drawing in which:

Figure 1 is a diagrammatic view showing the circuit with the elements of the circuit shown in section for illustrating the circulation through the various valves.

Figure 2 is a face view of the selector dial means and gear shift control means.

Referring to the drawing, the gear shifting 'system includes an oil pump 5, a shut-off`valve 6, a shifting valve 1, a selector valve 8, and gear shifting cylinders 9. The valves are in the circuit in the order named. The shifting power is represented by the oil pressure delivered by the pump to the shifting cylinders. Therefore, with the shut-off valve closed, the gear shifting system is ineffective.

Although only one gear shifting unit and one gear cluster are illustrated, it is obvious that a plurality may be used. The gear cluster to be shifted is indicated atv IIl and is slidably mounted on a .splined shaft I I. To retain the cluster in engaged or disengaged positions, the splined shaft is provided with detent means shown v in dotted lines at I2. AThe gear shifting unit comprises two cylinders I3 and I4, one at each end of a plunger I5. A yoke I6, engaging a groove in the gear cluster is pinned to the plunger at I'I. Thus, to move the cluster for a desired shift, one cylinder is charged as thel other one is exhausted.

The pump 5 draws oil from a sump, indicated at I8, through an intake line I9, and delivers it under pressure through a line 20 to the shut-off valve 6. The shutolf valve is open only when` the lever 2|, which controls the forward and reverse clutches (not shown) of the drive means to the transmission, is in neutral. Consequently, oil pressure is permitted -to pass.I through .the shut-'off valve to the other valves in the circuit to effect a shift only when the gears in the transmission are entirely disconnected from the drive means. y

'I'he shut-olf valve comprises a plunger 22 which slides in a cylinder 23 in a casing 24. The

plunger includes two grooves. When the valve is closed, one of the grooves 25 is in communi,- cation with the pressure line 20 from the pump. At this time, the other groove 26 is in communi- .cation with the sump through an exhaust line 21, and the shifting valve 1, through a linei. The plunger' is under the influence of a coil spring 29 which tends lto move the. plunger to connect the lines 20, 28 through groove 25.

The end of the plunger opposite the coil spring is tapered and extends from the casing 24 to contact the face of a cam 30 which is fixed tothe When the control lever is in forward or reverse positions, the high sections 3I of the cam facecontact the plunger, thus forcing the plunger back into the casing against the pressure of the coil spring for clos. ing the valve. When the control lever is in neutrai, the low section 3Ia of the cam face contacts the plunger, thus permitting the spring to force the plunger outwardly to open the valve.

The shifting valve l is controlled by a selector handle 32. It is eiective only when the shut-off valve connects lines 20 and 28.'

The shifting valve comprises a body 33 in which a plunger 34 slides, and a casing 35 in which the body 33 is rotatively journalledf, The bodyv extends from the housing and includes a gear 36 and a pointer element 31 both of which are formed integrally with or xed to the body and rotate with it.-

The selector handle 32 is pivoted on a pin 38y in a slot 39 inthe pointer element. The pivot point is to one side'of the center of rotation ments.

`and 43.

.of the plunger 34 extends from the casing into the slot in the pointer element and is contacted by a boss 49 on the underside of the handle 32. The plunger 34 has two sections of different diameters. The smaller diameter is provided with an annular groove 4I. The larger diameter is provided with two annular grooves 42 A coil spring 44 under compression, between the inner end of the plunger and the end of the casingbore, tends to hold the plunger 34 out against the selector handle. When in this position, the groove 4I in the smaller diameter section of the plunger is in communication with -the sump I8 through .an exhaust line 45.

The

groove 42 in the larger-diameter section is in communication with the line 28 from the shutoff valve through two ports 46 and 41. The groove 43 is in communlcationwith the sump through anexhaust line 48 and with the speed selector valve through a pressure linev 49. When the plunger 34 is in its second position, i. e. when' the selector handle has been pushed in, the exhaust line 45 is closed, line'28 is open to groove 4| through port 46 and to line 49 through port 41, and the exhaust line 48 is closed. The operation of this valve, in relation to the circuit, will be Vdiscussed below.

As stated above, the plunger 34 of the shifting valve 1 has two different diameters. The differential exists just beyond the 4groove 4I. When the plunger is i'n its out position, the'shoulder 56 between the portions of different diameter abuts a shoulder vin the body 33. When the selector handle is pushed in, the shoulder 50 on the plunger is moved between the two ports 46 and 41. Thus with the shut-oir valveopen, oil pressure is admitted to groove 4I through port 46. At this time, the exhaust line 45 has been closed and groove 42 has been moved to include port41 and the opening to line 49. Due to the difference in areas, as provided by the shoulder at 56, the oil pressure overcomes the spring presf sure and holds the plunger in.

When the selector handle is pushed in with the shut-olf valve closed, no pressure exists in groove 4I. Under these circumstances, the coil spring 44 returns the plunger and handle to their out positions just as soon -as the operator releases the handle.

The gear 36 meshes with a gear 5| keyed to the end of a shaft 52. The speed selector valve includes a rotary valve element 6I to which the shaft 52 is directly connected. Gears 36 and 5I are identical. Thus, since gear 36 rotates with the pointer, the rotary speed selectorvalve also rotates with the pointer.` Naturally, the gear link causes a reverse motion between the two. but they maintain relative positions as they rotate. A stationary dial'53 is provided for the pointer, indicating the positions of the selector valve.

The rota-ry selectorvalve distributes and relieves the oil pressure in the correct shifting cylinders to shift the gear clusters in the trans-- mission into the speed corresponding to the positions indicated on the dial. This description discloses only one such position since the construction of these rotary valves is well understood in the art. The rotary valve is journalled in a, casing 54 and includes two longitudinal passages, an exhaust .passage 55 open at all times through a line 56 to the sump, and a.

pressure passage 51 open at all times. to the pressure line 49, of the circuit.

The line 49 is incommunication constantly with an annular groove 60 inthe periphery of the rotary valve element 6I. A port 62 extends radially from this groove into the passage 51.

Another port 63 extends radially from this passage 51 and is adaptedto register with a port 64 into which line 65 is connected. This line 65 extends to the cylinder I4 of the shifting unit. -Another port (not shown) extends from the passage 51 for registry with a port 66 into which the pipe 61 is connected leading to cylinder I3 of the shifting unit. Each of these'pipes 65, 61

will register with respective exhaust ports one of which is shown at 68. As shown, exhaust of cylinder I3 is taking place through port 68.

Operation With the clutch lever 2I in" either forward or reverse position, the shut-off valve 6 is closed lever 2 I 'is moved into neutral many times during this period.

To effect a change, the selector handle 32 must 'be pushed in while the clutch lever is in neutral. The selector lhandle is foolproof. If the operator should, by chance, push the selector handle in While the clutch lever is in either forward or reverse'position, the coil spring behind the plunger 34 would move the plunger the shifting valve to the selector valve.

out again.

As an example, letvus say that the selector mechanism is set to run at speed A. The forward clutch is engaged, the shut-oft valve is closed,

and the selector valve 8 is still set to align the necessary ports' to effect the shift resulting inl speed'A. The gear cluster at this time is being held in its respective position by the detent I2. While the machine is running at speed A, the operator may set the selector mechanism, by turning the selector handle 32, for speed B. The

only change in the circuit takes place in the selector valve 8. Here, the ports necessary to effect speed B, and the ports necessary to disengage the gears of speed A are aligned. If the operator desires to continue at speed lA for several operations, he may do so as long as he does not push in the selector handle while the clutch control handle -is in neutral, l

Now, when the operator wants to change to the preselected speed 'B, he throws the clutch control lever into neutral. This opens the shut-oil' valve 6, directing oil pressure through line 28 to theshifting valve 1. He then pushes in the selector handle to direct the oil pressure through The selector handle remains in, due to the oil pressure on the differential plunger 34. IThe oil pressure is directed to the shifting cylinders through the line 49 to the selector valve 8, which had been previously set for speed B. As soon as the clutch lever is moved out of neutral the pressure I.the

including ports connecting its exterior toits bora an axially shiftable valve element disposed 'in said rotatable element and on its axis, a"l ever for rotating said rotatable tubular element, said lever engaging said valve element and being depressible for moving said valve element axially, a rotatably mounted selector valve adapted t be supplied with iluid from said discharge ports of said valve body, and a transmission connection from said rotatably mounted element to said selector valve for rotating said selector valve when said rotatably mounted element is rotated.

2. A valve mechanism for shifting gears comprising; a stationary cylinder, a rotatable cylinder mounted in said stationary cylinder, said rotatable cylinder and said stationary cylinder including ports constantly in communication for delivering fluid to the bore of said 3 whereby the valve element may be translated by means of the lever, and a selector.l valve, said selector valve and rotatable cylinder being connected by a transmission forirnparting movement to said selector-'valve when said rotatable cylinder is rotated and said selector valve being adapted to be supplied with iiuid from said ports in said rotatable cylinder controlled by said translatable .valve element.

Asupply conduit means in said casing controlled by translation of said shifter valve, said casing being rotatably mounted, a valve body containing said rotatably mounted casing, there being pasrotatable cylinder, a valve element translatably mounted in the bore of said rotatable cylinder, said rotatable cylinder including an indicator i'lnger, xed to and projected radially from its outer end, an indicator plate xed relative to said nger, a lever pivotally mounted toward the end of said indicator iinger for swinging movement Aagainst the end of said translatable valve element, said indicator nger including a radial slot containing said lever, whereby said rotatable cylinder may be rotated by means of the lever or sageways and ports arranged in said valve body and casing for delivering iluid to the bore of said casing, an indicator dial, an indicator finger xed to said rotatable casing and movable relative to said dial, a transmission connection between said casing and said selector valve for transmitting motion from said casing to said selector valve, means for delivering iluid under pressure through said shifter valve to said selector valve, and a lever pivotably mounted on said nger for swinging motion longitudinally of the axis of the shifter valve, said inger engaged with said casing against relative rotation, whereby rotation of the lever will rotate said nger, said lever dis- A posed in contact with the shifter valve and, said yshifter valve being spring urged against the lever,

whereby when the lever is rotated, the selector valve is set, and when the lever is depressed, the shifter valveis operated to admit the iiuid to the selector valve for an appropriate shift.

WILLIAM JG. HOELSCHER. 

